Sunday saw the start of the winter series – often the most closely contested series because it doesn’t have the interruptions of summer holidays, open meeting etc. More on the race later.
For those new to this we split into two series, Nov/Dec and then for the hardy folk Jan-Mar when the water is a bit chillier. Autumn traditionally brings stronger winds so it’s worth revisiting techniques for stronger winds…
Once you are fully hiked out, or at least as far as you are comfortable, there is nothing else you can do to add more leverage, so if the boat is not upright you must reduce the force from the sails trying to turn you over. That seems just common sense, but it is very easy to ‘hang on hard’ and let the boat heel over. of course that does slightly reduce the force because the sail isn’t upright and some of the air flows up off the sail instead of driving forwards, but it is a really slow way to sail. In a traditional keelboat it makes sense to have some heel because the weight of the keel becomes more effective as you heel, so for them it is a balance between more heel gives more righting effect from the keel but less efficiency from the sails. The right angle for a traditional keel boat in strong winds might be 30 degrees – more than that and performance still suffers. So we’ve all seen great pictures of big boats heeled over charging along. They look great, but they are NOT dinghies. We need to clear that image right out of our heads. Dinghies go fast when they are upright. OK so we’ve got that out of the way – how do we reduce power?? That depends on the point of sailing, but there are two things we can change:
· the shape of the sail
o all our sail controls
· the angle of the sail
o How hard we sheet in
o The direction we point the boat (especially upwind)
In general the fuller the sail (the bigger/deeper curve we have from front to back) the more power – but the direction of that power may not be good. When most of the force is forwards and there is still flow over the sail (reaching) a full sail is good. Upwind too much force may be generated sideways and not enough forwards, and you can’t get the narrow angle of attack at the front of the sail. Upwind the flatter we make the sail the closer we can sail against the wind and the less force generated.
Think of an aircraft taking off – full flaps for a big wing with a lot of depth. Lots of lift, but also lots of drag – needs full power on the engines. Also with that heavily shaped wing the aircraft is tilted to a significant angle (you feel the plane tilt as the pilots ’rotate’ on take-off. That alters the angle of the wing compared to the air flow. That’s what we have to do if we have a very full sail – we can’t point close to the wind but we do make a lot of power. Once the aircraft is moving fast the flags are taken in and a lower drag wing is used and the plane levels off so there is a shallow angle in the wing. That’s like point close against the wind for a sail.
Sail shape we can do the same – cross wind for maximum power we increase the draft of the sail (ease outhaul to make the bottom fuller, ease Cunningham, reduce kicker to reduce mast bend and make the middle of the sail fuller). Upwind with the maximum wind over the sail we need a flatter sail, and in stronger winds we reduce the power by making it even flatter. We also try to reduce the force at the top of the mast by letting the top of the sail twist. You would think that we would let the top twist by less kicker/less mainsheet tension from the centre, but actually it works better to do it by adding Cunningham which makes the mast bend and keeping the mainsheet tension high with the traveller out slightly for most sails. What we are trying to do is the same – a flat sail with the top allowed to feather on the gusts – that’s why the mast is tapered so the top can bend in gust response, the Cunningham really helps this by making the mast a bit like a bow. Tighten the bow string (pull in the luff) and the bow arcs. Tighten the Cunningham and the mast bends – as the top of the mast comes back it eases the top of the leech and as the middle of the mast bends forward it flattens the middle of the sail.
Sail angle (especially upwind)
There are two ways to change the sail angle – we can let the traveller out a bit (or ease mainsheet) or we can point the boat closer to the wind. In practice we do a bit of both. Ease sheet briefly as a gust strikes upwind and luff slightly to change the angle. Doing that we can keep the boat flat – I often mutter to myself ‘Flat is fast; Fast is high’ meaning we HAVE to keep the boat flat and doing that helps the boat go fast through the water. Going fast through the water makes the foils work better so you end up tracking higher.
So – Sunday mornings race – Off the line just Gareth, Peter H and Paul. The wind was regularly gusting into the 20 knot range so we were in ‘over-powered’ conditions. Long beat from 1 to 7 – in those conditions you can’t roll tack – you always lose some ground. With full rake on I have to stay on the side tank bending forwards until the boom brushes over me (keep head well down!). Then I push off hard and almost jump to the new tack. This takes practice! You need to get the boat flat and driving on the new tack very quickly to avoid getting pushed up into ‘irons’ (stuck head to wind). It can pay to slightly ease kicker and definitely to ease the main a bit to help the boat get right round but I often don’t have time to do the kicker. So, first beat I went for a port end on port – saw Paul coming down the line to shut me out so I ducked him but crossed Peter – up this leg I went right, Paul up the middle and Peter left - VERY EVEN in fact Peter H looked to probably have the best beat although he didn’t risk trying to tack under Paul near the windward mark. Paul 1st, Peter 2nd, Gareth 3rd but only about 4 lengths between the three of us. Here’s where a bit or pre-planning helped – I knew that the course to 3 was a dead run so I bore away quicker and slipped past Peter who was initially sailing more towards mark 5 than 3. Paul also went a bit high but had enough lead to stay clear and we all arrived at the leeward mark in close order, Paul, Gareth, Peter. The round-up from a dead run to a beat really matters, Paul made a good rounding, Gareth close behind and able to stay high clear of his wind shadow, but Peter rounded a bit wider and dropped into the backwind of Gareth and Paul and slipped back. It’s really important to round up close to a leeward mark or you can lose a lot of ground – start wider and aim to pass the mark really close already beating. (Not sure what happened to Peter after that, I was too busy chasing Paul!) Up the beat to 5 and again almost nothing in it. I continued to chase Paul and we stayed within a few lengths all the way round the second lap until the start of the third beat. Paul rounded up at mark 1 just ahead in a massive gust. I rounded on his tail just a shade closer to the mark (I started a bit wider and wound up a tad closer – not that Paul did a bad rounding, I just managed to creep about a boat width to windward. This time I left the plate angling back a lot which made the boat more balanced. This seemed to make it much easier to sail the boat and I was able to creep to windward although Paul was still ahead and to leeward. When Paul tacked I tacked and we drag raced from somewhere in front of the club all the way to 7. The wind was shifty with violent gusts – usually I can sail to windward pretty much keeping the main in and playing the tiller to ‘feather’ up the edge of the wind, but with the shifting squally gusts I ended up playing the sheet the whole way – gust - ease to keep flat and accelerate, get speed, point up sheet in again, lull sheet in, bigger lull bear away gently (try to keep the boat moving and not over-react). I could hear Paul’s boat just to windward of me most of the way. Still very little in it but with the plate raked well back my boat felt much better. On the first lap I felt I was fighting the boat and the wind, on that lap I felt the boat wanted to surge forwards. After that again very little in it – I loosely covered Paul up the beats and made sure to stay on the inside for the next mark on the runs. We finished no more than a few lengths apart – great race which bodes well for the series. With Tony and Mike also back for the winter we could be looking at some really great racing if the weather cooperates. – Where were you Mark…
Sadly it seems Pauls was OCS (on course side) at the start but it was a heck of a good sail and deserved better!
I’ll tackle reaching and running in strong winds next time.
No excuse for being late next Sunday – Remembrance day we don’t start till after 11. let’s hope it is an easier day to sail than this week!